Master pencil mark strategies like Snyder Notation. Keep your board clean and discover advanced patterns like X-Wing and Naked Pairs faster.
As Sudoku puzzles get harder, keeping candidates in your head becomes impossible.
However, blindly writing candidate numbers into every cell clutters the board. Here are smart candidate management techniques used by top solvers.
A technique favored by speed solvers globally: only write candidate notes in a 3x3 block when a digit can go in EXACTLY TWO cells inside that block.
If there are 3 or more potential cells, leave it blank for now. This keeps your board tidy and makes pairs and line eliminations stand out instantly.
Whenever you place a final digit, immediately clear that candidate digit from every cell in its row, column, and 3x3 block.
When you reach late-game stages needing techniques like X-Wing or XY-Wing, transition to "Full Pencil Marks" where every valid candidate is listed across remaining empty cells.
